Liquid phase surface engineering of aluminum (AA6061) with Cr predeposited layer by pulsed Nd-YAG laser

In this study the feasibility of obtaining thin surface layer of chromium based intermetallic compounds on Al–6061 substrate was studied by using laser surface alloying (LSA). The initial layers of copper، nickel and chromium with a total thickness of 15 micrometers was electroplated on Al substrates and subsequently laser alloyed by using pulsed Nd: YAG at various output power and scanning rates with argon gas shielding. Analyses of samples using optical and scanning electron microscopy and X-ray diffraction (XRD) showed that adding nickel and chromium are suitable to reduce susceptibility of cracking and improving surface hardness of alloyed layer on aluminum due to the formation of intermetallic compounds such as Al11Cr2، Al2Cu، Al3Ni2. Microhardness test was performed on cross-sections of specimens and it showed a significant increase (6 times) in hardness of alloyed-layer compared to the Al substrate.